Electrical transport mechanism in VO2 thin films

Vanadium oxide (VO₂) transforms from a semiconductor phase to a metal phase at a temperature of 67°C. This phase transformation is accompanied by a dramatically change in its electrical and optical properties. Therefore, vanadium oxide thin films are very attractive for switching applications. This paper presents the optical and electrical properties of vanadium oxide thin films deposited by vacuum thermal evaporation of metallic vanadium following by oxidation. We have studied the electro-physical behavior of these VO₂ films during their phase transition. It was shown that the electrical transport mechanism of the obtained vanadium oxide films differs in low and high electrical fields. In low electrical fields, conductivity is obtained by the Schottky transport mechanism, whereas in high electrical fields conductivity ranges from Ohmic mechanism for relatively low fields, to Poole-Frenkel mechanism for higher fields. FTIR and near IR reflectance characteristics of the obtained films are presented.